How to solve mysterious system lockups?

[Garrett Cooper]

N. Harrington wrote:
> Hello
>   I have several systems that are used as squid
> caching servers. I have some systems that use SCSI
> disks and some  that use SATA disks. They are
> identical in everyway except for the sata vs SCSI
> drives. 
>
>  At random times, the sata based systems seem to be
> freezing. You can ping them and they respond, but you
> cannot log in. Nor are any logs processed during that
> time. 
>
>  I figure it mist be something to do with the disks,
> but I am not sure how to solve it. There seems to be
> little rhyme or reason. It does not happen necessarily
> during busy times. It can happen in the middle of the
> night.
>
>  Any pointers in how to track down the cause would be
> much appreciated.
>
>  Tyan S2881 Motherboard - 4gigs mem
>  Using 4 SATA (or scsi) drives
>  FreeBSD amd64 6.2-STABLE.
>
>  Thanks!
>
>   Nicole
>   
Nicole,
    What's the driver in use for the SATA and the SCSI drives?
-Garrett